Liquid crystal displays

ABSTRACT

The present invention provides a liquid crystal display including a substrate, a first gate line, a second gate line, an insulation layer, a data line, a passivation layer, a low dielectric constant layer, and a pixel electrode. The first gate line intersects with and is insulated from the second gate line. The pixel electrode overlaps a portion of the first gate line and a portion of the second gate line. The data line overlaps a portion of the first gate line. The portion of the first gate line overlapped by the pixel electrode is different from the portion of the first gate line overlapped by the data line. Therefore, the capacity effect between the pixel electrode and the data line is reduced.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority of Taiwan Patent ApplicationSerial No. 091124962 filed on Oct. 25, 2002.

FIELD OF INVENTION

[0002] The present invention relates to an LCD (Liquid Crystal Display)and its method of manufacture.

BACKGROUND OF THE INVENTION

[0003] Compared with a CRT (cathode ray tube) display, the LCD has theadvantages of less weight, smaller volume, and lower radiation. Hence,we can expect that the LCD will substitute the CRT display to be themost popular display.

[0004] Conventional LCDs include a liquid crystal panel and a back lightdevice. The liquid crystal panel includes a top substrate, a bottomsubstrate and a liquid crystal layer formed between the top substrateand the bottom substrate. The top substrate has a CF (Color Filter). Thebottom substrate has a TFT (thin film transistor). Beside, a toppolarizer is disposed on the top substrate and a bottom polarizer isdisposed between the bottom polarizer and the back light device.

[0005] A Black Matrix may be plated on a CF to increase contract andprevent mix of color and leakage of light. Hence, the LCD is better thanthe CRT display in resolution. However, if the resolution is promotedwithout the pitch of the pixels being narrowed, the aperture ratio ofpixels will be reduced and the brightness of the LCD will decrease.Hence, narrowing the Black Matrix or studying other methods to improvethe brightness is an important issue.

SUMMARY OF THE INVENTION

[0006] One aspect of the present invention is to provide an LCD withbetter aperture ratio and a method for manufacturing the LCD.

[0007] Another aspect of the present invention is to reduce thedisconnection caused by a signal line.

[0008] Still another aspect of the present invention is to avoid thelight leakage of the LCD.

[0009] The other aspect of the present invention is to reduce thecapacity effect between a signal line and a pixel electrode.

[0010] In the present invention, a first gate line and a second gate areformed on a substrate. The first gate line intersects with and isinsulated from the second gate line. After that, an insulation layer, asemiconductor layer, a data line, a passivation layer, a low dielectricconstant layer and a pixel electrode are formed sequentially. The dataline overlaps the first gate line. A dielectric constant layer is a lowdielectric constant layer. The pixel electrode overlaps with a portionof the first gate line and a portion of the second gate line. The dataline overlaps with a portion of the first gate line. The portion of thefirst gate line overlapped by the pixel electrode is different from theportion of the first gate line overlapped by the data line. Therefore,the capacity effect between the pixel electrode and the data line isavoided. In the second embodiment of the present invention, another kindof LCD is disclosed. The first gate line is replaced by a gate lineincluding a pair of gate lines that are parallel to each other andseparated by a gap.

[0011] The advantages and spirit of the present invention may be furthercomprehended through the following detailed description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The present invention is illustrated by way of example and notlimitation in the accompanying figures, in which like referencesindicate similar elements, and in which:

[0013]FIG. 1a is a schematic diagram of the first embodiment of thepresent invention;

[0014]FIG. 1b is a cross-sectional diagram along the line I-I′ of FIG.1a;

[0015]FIG. 1c is a cross-sectional diagram along the line II-II′ of FIG.1a;

[0016]FIG. 2a is a schematic diagram of the second embodiment of thepresent invention;

[0017]FIG. 2b is a cross-sectional diagram along the line III-III′ inFIG. 2a;

[0018]FIG. 2c is a cross-sectional diagram along the line IV-IV′ of FIG.2a.

DETAILED DESCRIPTION

[0019]FIG. 1a is a schematic diagram of the first embodiment of thepresent invention. The LCD of the present invention includes a pluralityof first gate lines 11, a plurality of second gate lines 12, a pluralityof data lines 19 and a plurality of pixel electrodes 13. Only one of thepixels is illustrated in FIG. 1a. The first gate line 11 intersects withand is insulated from the second gate line 12. The data line 19 overlapsa portion of the first gate line 11. The pixel electrode 13 alsooverlaps a portion of the first gate line 11 and a portion of the secondgate line 12. However, in the first gate line 11, the overlappingportion of the data line 19 is different from the one of the pixelelectrode 13.

[0020]FIG. 1b is a cross-sectional diagram along the line I-I′ of FIG.1a. On a substrate, such as a glass substrate, the first gate line 11,an insulation layer 15, a semiconductor layer 17, a data line 19, apassivation layer 21, a low dielectric constant layer 23 and a pixelelectrode 13 are formed sequentially. Obviously, the portion that thedata line 19 overlaps the first gate line 11 is different from theportion that the pixel electrode 13 overlaps the first gate line 11.

[0021]FIG. 1c is a cross-sectional diagram along the line II-II′ of FIG.1a. In the present invention, the second gate line 12 and the insulationlayer 15 are formed sequentially on the substrate 100. Thus, after thesemiconductor layer 17 and the data line 19 are formed as illustrated inFIG. 1b, the passivation layer 21, the low dielectric constant layer 23and the pixel electrode 13 are formed sequentially. As shown in FIG. 1c,the pixel electrode 13 overlaps a portion of the second gate line 12.

[0022] In the present invention, the material of the insulation layer 15includes a Si₃N₄ layer depositing above the first gate line 11, thesecond gate line 12 and the substrate 100. The material of thesemiconductor layer 17 includes an undoped Si amorphous layer and adoped Si amorphous layer. The material of passivation layer 21 includesSi₃N₄. The low dielectric constant layer 23 is a transparent materialwith low dielectric constant, such as the acrylic. The material of thepixel electrode 13 includes ITO (Indium Tin Oxide).

[0023]FIG. 2a is a schematic diagram of the second embodiment of thepresent invention. In the present invention, an LCD includes a pluralityof gate line pairs 31, a plurality of gate lines 32, a plurality of datalines 39 and a plurality of pixel electrodes 33. Only one pixel isillustrated in FIG. 2a. The gate line pair 31 intersects with and isinsulated from the gate line pair 32. The gate line pair 31 includes afirst gate line 311 and a second gate line 312. The first gate line 311parallels the second gate line 312 with a gap 314 therebetween. The dataline 39 overlaps a portion of the gate line 31 and the gap 314. Besides,the pixel electrode 33 also overlaps a portion of the gate line pairs31. However, in the gate lines 31, the overlapping portion of the dataline 39 is different from the same of the pixel electrode 33. Likewise,the pixel electrode 33 also overlaps a portion of the gate line 32.

[0024] In the second embodiment, as shown in FIG. 2a, the data line 39overlaps the gap 314 of the gate line pair 31 and a portion of the gateline pair 31. The pixel electrode 33 overlaps a portion of the secondgate line 312. The pixel electrode 33 overlaps a portion of the firstgate line 311.

[0025]FIG. 2b is a cross-sectional diagram along the line III-III′ ofFIG. 2a. On a substrate, such as a glass substrate, the first gate linepair 31, an insulation layer 35, a semiconductor layer 37, a data line39, a passivation layer 41, a low dielectric constant layer 43 and apixel electrode 33 are formed sequentially. Obviously, the portion thatthe data line 39 overlaps the first gate line 31 is different from theportion that the pixel electrode 33 overlaps the first gate line 31.

[0026]FIG. 2c is a cross-sectional diagram along the line IV-IV′ of FIG.2a. In the present invention, the gate line 32 and the insulation layer35 are formed sequentially on the substrate 300. Thus, after thesemiconductor layer 37 and the data line 39 are formed as illustrated inFIG. 2b, the passivation layer 41, the low dielectric constant layer 43and the pixel electrode 33 are formed sequentially. As shown in FIG. 2c,the pixel electrode 33 overlaps a portion of the gate line 32.

[0027] In the present invention, the material of the insulation layer 35includes a Si₃N₄ layer depositing above the data line pair 31, the gateline 32 and the substrate 300. The material of the semiconductor layer37 includes an undoped Si amorphous layer and a doped Si amorphouslayer. The material of passivation layer 41 includes Si₃N₄. The lowdielectric constant layer 43 is a transparent material with lowdielectric constant, such as the acrylic. The material of the pixelelectrode 33 includes ITO (Indium Tin Oxide).

[0028] The structure of an LCD proposed in the present invention mayeffectively increase the aperture ratio and avoid the leakage of light.Moreover, it may reduce the disconnection caused by a signal line toreduce the capacity effect between a signal line and a pixel electrode.

[0029] In the foregoing specification, the invention has been describedwith reference to specific embodiments. However, various modificationsand changes can be made without departing from the scope of the presentinvention as set forth in the claims. Accordingly, the specification andfigures are to be regarded in an illustrative rather than a restrictivesense, and all such modifications are intended to be included within thescope of present invention as claimed.

1. A liquid crystal display, comprising: a substrate; a first gate line,comprising a first portion and a second portion; a second gate line,said first gate line and said second gate line being disposed on saidsubstrate and being insulated from each other; an insulation layerdisposed above said first gate line and said second gate line; a dataline, said data line and said first portion overlapping, said insulationlayer being disposed between said data line and said first portion; anda pixel electrode disposed above said data line, said pixel electrodeand said second portion overlapping.
 2. The liquid crystal displayaccording to claim 1, wherein said first portion is different from saidsecond portion.
 3. The liquid crystal display according to claim 1,wherein said pixel electrode and said second gate line overlap.
 4. Theliquid crystal display according to claim 1, wherein said liquid crystaldisplay further comprises a semiconductor layer disposed above saidinsulation layer, said semiconductor layer comprises an undopedamorphous silicon layer and a doped amorphous silicon layer.
 5. Theliquid crystal display according to claim 1, wherein said liquid crystaldisplay further comprises a passivation layer disposed above said dataline.
 6. The liquid crystal display according to claim 1, wherein saidliquid crystal display further comprises a low-dielectric-constant layerdisposed above said passivation layer.
 7. The liquid crystal displayaccording to claim 1, wherein said first gate line comprises a pair ofgate lines, said pair of gate lines are parallel to each other andseparated by a gap.
 8. The liquid crystal display according to claim 7,wherein said data line, said gap and a part of said pair of gate linesoverlap.
 9. A liquid crystal display, comprising: a substrate; a firstgate line, comprising a first portion and a second portion; a secondgate line, said first gate line and said second gate line being disposedon said substrate and being insulated from each other; an insulationlayer disposed above said first gate line and said second gate line; adata line, said data line and said first portion overlapping, saidinsulation layer being disposed between said data line and said firstportion; and a pixel electrode disposed above said data line, said pixelelectrode and said second portion overlapping; wherein said firstportion is different from said second portion.
 10. The liquid crystaldisplay according to claim 9, wherein said pixel electrode and saidsecond gate line overlap.
 11. The liquid crystal display according toclaim 9, wherein said liquid crystal display further comprises asemiconductor layer disposed above said insulation layer, saidsemiconductor layer comprises an undoped amorphous silicon layer and adoped amorphous silicon layer.
 12. The liquid crystal display accordingto claim 9, wherein said liquid crystal display further comprises apassivation layer disposed above said data line.
 13. The liquid crystaldisplay according to claim 9, wherein said liquid crystal displayfurther comprises a low-dielectric-constant layer disposed above saidpassivation layer.
 14. The liquid crystal display according to claim 9,wherein said first gate line comprises a pair of gate lines, said pairof gate lines are parallel to each other and separated by a gap.
 15. Theliquid crystal display according to claim 14, wherein said data line,said gap and a part of said pair of gate lines overlap.
 16. Amanufacture method of a liquid crystal display, said method comprising:providing a substrate; forming a first gate line and a second gate line,said first gate line and said second gate line being disposed on saidsubstrate and being insulated from each other; forming an insulationlayer disposed above said first gate line and said second gate line;forming a data line, said data line and a first portion of said firstgate line overlapping, said insulation layer being disposed between saiddata line and said first portion; forming a passivation layer disposedabove said data line; forming a low-dielectric-constant layer disposedabove said passivation layer; and forming a pixel electrode disposedabove said low-dielectric-constant layer, said pixel electrode and asecond portion of said first gate line overlapping; wherein said firstportion is different from said second portion.
 17. The liquid crystaldisplay according to claim 16, wherein said liquid crystal displayfurther comprises a semiconductor layer disposed above said insulationlayer, said semiconductor layer comprises an undoped amorphous siliconlayer and a doped amorphous silicon layer.